I was wondering if one could set up a RAID-5 array such that only some space of the third disk is used in the raid array and the left over space can be used as a non-raid volume.
I have three HDDs with 2TB, 2TB and 3TB. The 1TB on Disk 3 should still be usable but not redundant. (on an ubuntu server)
The following image shows what I'm trying to achieve: Raid Setup (orange = raid; green & blue = normal Volumes)
Is this possible or can disks which are part of a raid-array in their entirety only be used within the raid?
Best Answer
Firstly don't use RAID 5 at all, it's very well documented how dangerous it is, especially with large slow, especially consumer, HDD's - it's been considered dangerous for over a decade now and it frankly upsets me seeing it still being an option on disk controllers and even in software.
Anyway what you want to achieve isn't usually possible with hardware disk controllers, you could probably make software RAID work like this but it wouldn't be advisable, I'm sure it'd be fragile and hard to rebuild when the inevitable disk failure happens.
Just buy the extra disks to run this as a R6 or R10, knowing you have a supportable and stable platform.